I'm going to say this isn't so simple as you pretend. I had an existing WDS network with 802.11g devices (AExtreme + 2 Expresses) that I had to disable when I got my time capsule (which replace the AExtreme). I have spent several hours over the last two weeks trying to make WDS work with the Time Capsule as the main and one Express as a remote - I have wireless with the main but the Express disappears from Airport Utility and is flashing yellow - error status. This may be simple if you go buy all new hardware, but currently I don't have functional WDS and management for multiple base stations.